This invention relates to improving video and graphics processing.
At low display refresh rates (for example, 50 fields/sec for interlaced video material, and 24 frames/sec for film-originated material) on digital display devices, a display artifact referred to as “area flicker” can occur. The area flicker becomes more visible as the size of the display increases, due to the high sensitivity to flicker in the human visual peripheral region. A simple solution for reducing the area flicker is to increase the display refresh rate by repeating the input fields or frames at a higher rate (for example, 100 fields/sec for interlaced video). This solves the area flicker problem for static scenes. However, the repetition introduces a new artifact in scenes with motion, known as “motion judder” or “motion smear,” particularly in areas with high contrast, due to the human eye's tendency to track the trajectory of moving objects. For this reason, motion compensated frame interpolation is preferred, in which the pixels are computed in an interpolated frame or field at an intermediate point on a local motion trajectory, so that there is no discrepancy between an expected image motion due to eye tracking and a displayed image motion. A motion vector describes the local image motion trajectory from one field or frame to the next.
Motion vectors can be computed at different levels of spatial resolution, such as at a pixel level, at an image patch level, or at an object level. Computing a motion vector for every pixel independently would theoretically result in an ideal data set, but is unfeasible due to the large number of computations required. Computing a motion vector for each image patch reduces the number of computations, but can result in artifacts due to motion vector discontinuities within an image patch. Computing motion vectors on an object basis can theoretically result in high resolution and lower computational requirements, but object segmentation is a challenging problem.
Therefore what is needed is a way to determine and use motion vectors efficiently and accurately, such that little or no discrepancy exists between an expected image motion due to eye tracking and a displayed image motion in a digital video.